Mobile communication device often require input of character sequences, including device passwords, smart card PINs, SIM pins and the like, via an input dialog box provided at the display device from a lock screen. Many mobile communication devices are also enabled to allow emergency calls, such as 911 calls, from the lock screen. Indeed, in some jurisdictions, such functionality is legislated, in that character input such 911, 999, 112, 008, etc. causes an emergency call to be placed and/or to bring up an emergency call dialog box. Moreover, different keyboards map these numbers to different letters, and input of the mapped characters can also cause the emergency call to be placed: for example 911 can be mapped to “cww”, and determination of receipt of “cww” triggers the 911 call and/or the emergency call dialog. Hence, if character sequences contain emergency number sequences, then the emergency call dialog box will appear in front of the input dialog box asking that the “Send” button be pressed to make the emergency call. The emergency call dialog box must then be dismissed, for example by pressing any button other then the “Send” button to dismiss the dialog before the remainder of the password is received and/or access is granted to the device. Such a situation can force use of passwords that do not contain emergency character sequences, but also is a general waste of processing resources as the communication device is unnecessarily placed in an emergency call ready mode and/or wastes computing resources to provide the emergency call dialog box and/or causes an erroneous emergency call to be placed. The latter is a further waste of bandwidth, as well as a waste of resources at an emergency call centre as the erroneous call is received and processed, for example by a call centre management system. Such a call can also result in a delayed response to legitimate emergency calls.